Evidence is rapidly accumulating that urban residents are at a far higher risk of malaria than previously acknowledged. But, research on the underlying processes associated with urban malaria is limited and urban malaria control measures are based on the assumption that risk factors identified in rural areas also apply in the urban areas. Our long-term goal is to identify urban groups at high risk of malaria as a prerequisite to developing effective, targeted malaria control methods. The specific hypothesis is that population movement, in the form of travel of urban residents to rural areas, is responsible for the bulk of urban malaria in Ndirande Township, Blantyre, Malawi. The hypothesis is based on the following observations: children from Ndirande who had recently traveled to rural areas were six times more likely to have clinical malaria than children who had not;a cross-sectional entomological survey failed to capture any malaria vectors in the area;polluted breeding sites in the area are unlikely to support mosquito breeding. The focus of this proposal is to understand the role that population movements have on the burden of malaria in urban areas. The specific aims and associated experimental designs are: 1. Determine whether and to what extent population movements increase the risk of malaria illness in Ndirande Township, Blantyre, Malawi. We will conduct a longitudinal study, with "malaria illness" and "time to malaria illness" as the main study outcomes. 2. Evaluate the spatial patterns of malaria illness and the environmental determinants. If the bulk of transmission is occurring outside of Blantyre, the distribution of cases in Ndirande should be random (i.e., not clustered around potential breeding sites). All malaria cases identified from the local clinic and potential breeding sites identified through satellite imagery and ground truthing will be georeferenced in a CIS and analyzed for spatial clustering of malaria. 3. Determine the density of anopheline mosquitoes in Ndirande and calculate the annual entomological inoculation rate (EIR) for the area. To verify whether malaria cases were locally infected, we will conduct yearlong entomological surveys in the area to assess the density of anopheline mosquitoes in relation to humans and calculate EIR.